U.S. Cardinal Raymond L. Burke marches with pro-life demonstrators during the third annual national March for Life in Rome May 12.

VATICAN CITY (CNS) — U.S. Cardinal Raymond L. Burke and U.S. pro-life leaders joined tens of thousands of demonstrators in Italy's third annual March for Life May 12, which ended with a personal greeting from Pope Francis.

According to organizers, some 30,000 marched along the route from the Colosseum to Castel Sant'Angelo, a distance of nearly two miles. They followed a large wooden cross decorated with replicas of unborn children, and carried signs bearing messages such as "Let's not kill the future" and "Stop silent genocide."

Rome Mayor Gianni Alemanno and Maurizio Gasparri, vice president of Italy's Senate, were among the participants.

Many of the marchers had reached the end of the route by 11:30 a.m., when Pope Francis acknowledged them before praying the "Regina Coeli" in St. Peter's Square, at the other end of Via della Conciliazione from Castel Sant'Angelo. The pope called on the marchers to "keep the attention of everyone on the important issue of respect for human life from the moment of conception."

The pope also praised a petition drive in support of the pan-European "One of Us" initiative, which he said would "ensure legal protection to the embryo, protecting every human being from the first moment of existence"; and he noted the pro-life "Evangelium Vitae" pilgrimage, to take place at the Vatican June 15 and 16.

After leaving the square, Pope Francis rode in the popemobile down Via della Conciliazione, where he was met by many participants in the march.

Jeanne Monahan, president of the U.S. March for Life Education and Defense Fund, took part in the Italian event, as did Lila Rose, president of the U.S. pro-life group Live Action.

The day before the march, organizers held a daylong conference at Rome's Regina Apostolorum University, featuring talks on bioethics by medical scientists and presentations by Cardinal Carlo Caffarra of Bologna, Italy, and Archbishop Giampaolo Crepaldi of Trieste, Italy.